非线性传输线产生射频脉冲原理研究

介绍了非线性传输线的工作原理和色散特性,给出了用于模拟交叉耦合磁饱和非线性传输线的计算方法。算法基于传输线各节点的时域差分方程组进行步进迭代,其中利用J-A模型描述传输线中NiZn铁氧体磁芯的非线性磁化行为,并模拟了非线性传输线的工作方式。实验获得了中心频率165MHz的宽带脉冲输出,初步验证了用于产生宽带电磁脉冲的非线性传输线关键技术。     

空间太阳阵二次放电的模拟实验研究

二次放电是造成空间高压大功率太阳阵功率损失的主要原因.通过地面模拟实验研究，确定 了二次放电阈值电压并监测了二次放电脉冲电流，对高压太阳阵二次放电特性及其击穿机理 进行了讨论.结果表明，高压太阳阵工作电压和电池串间电流的提高增加了高压太阳阵发生 二次放电事件的可能性；通过采用特殊的结构设计和在太阳阵电池串之间涂覆RTV胶，可以 有效抑制二次放电事件的发生. 关键词： 高压太阳阵 空间静电放电 二次放电     

A voltage trade study for the design of capillary electrophoresis instruments for spaceflight

Capillary electrophoresis (CE) systems have undergone extensive development for spaceflight applications. A flight-compatible high voltage power supply and the necessary voltage isolation for other energized components can be large contributors to both the volume and mass of a CE system, especially if typical high voltage levels of 25–30 kV are used. Here, we took advantage of our custom CE hardware to perform a trade study for simultaneous optimization of capillary length, high voltage level, and separation time, without sacrificing method performance. A capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C⁴D) method recently developed by our group to target inorganic cations and amino acids relevant to astrobiology was used as a test case. The results indicate that a 50 cm long capillary with 15 kV applied voltage (half of that used in the original method) can be used to achieve measurement goals while minimizing instrument size.     

Vacancy effects on one-dimensional migration of interstitial clusters in iron under electron irradiation at low temperatures

We performed in situ observation of one-dimensional (1D) migration of self-interstitial atom (SIA) clusters in iron under electron irradiation at 110–300 K using high-voltage electron microscopy. Most 1D migration was stepwise positional changes of SIA clusters at irregular time intervals at all temperatures. The frequency of 1D migration did not depend on the irradiation temperature. It was directly proportional to the damage rate, suggesting that 1D migration was induced by electron irradiation. In contrast, the 1D migration distance depended on the temperature: distribution of the distance ranged over 100 nm above 250 K, decreased steeply between 250 and 150 K and was less than 20 nm below 150 K. The distance was independent of the damage rate at all temperatures. Next, we examined fluctuation in the interaction energy between an SIA cluster and vacancies of random distribution at concentrations 10^?4–10^?2, using molecular statics simulations. The fluctuation was found to trap SIA clusters of 4 nm diameter at vacancy concentrations higher than 10^?3. We proposed that 1D migration was interrupted by impurity atoms at temperatures higher than 250 K, and by vacancies accumulated at high concentration under electron irradiation at low temperatures where vacancies are not thermally mobile.     

Obstacles for one-dimensional migration of interstitial clusters in iron

Interstitial clusters are known to cause frequent one-dimensional (1D) jumps (stepwise positional changes) under electron irradiation around room temperature. The distance of 1D jumps in iron was examined in detail through in-situ observation using high-voltage electron microscopy. The 1D jump distance was found to be longer for smaller clusters in specimens of higher purity, although the distance did not depend on the irradiation beam intensity and electron energy. The distribution of the 1D jump distance was well described by the distribution of the free path of interstitial clusters migrating through randomly distributed impurity atoms. The 1D jump process is considered as fast 1D diffusion of interstitial clusters at low activation energy from the point where the cluster detrapped from an impurity atom to the point where the cluster was trapped again by another impurity. Electron irradiation provides a trigger for causing 1D migration by detrapping of clusters from impurity atoms.     

高压击穿铜丝物相研究

采用高压放电的方式对材料进行击穿,可以方便地制造纳米颗粒．搭建了高压击穿实验装置,对铜丝进行高压击穿实验;分别采用透射电子显微镜（TEM）、扫描电子显微镜（SEM）和元素能谱（EDS）、X射线衍射（XRD）测试,对铜丝击穿丝状物进行了形貌和成份分析．研究了铜丝高压击穿后的物相特性．研究结果发现,在高压作用下铜丝被充分电离,产生丝状分布,其构成为纳米颗粒的凝结;纳米颗粒的直径分布主要集中在30—60nm之间;颗粒产物由铜元素和氧元素组成;它们以单晶Cu,Cu2O和CuO组成混合物;粒径大小、产物成分与铜丝长度、直径及电压等因素相关．     

100 kV重复频率高压脉冲电源

为研究气体间隙的放电特性,设计了输出幅度在30～100 kV、重复频率1～5 kHz可调的高压脉冲电源。利用谐振充电的原理,将10 kV的初级电源的能量转移到中储电容,中储电容的电压升高到至少18 kV。在光触发信号的作用下,氢闸流管导通,中储电容上的能量通过脉冲变压器放电,在脉冲变压器的副边得到最大幅度为100 kV的负脉冲,其脉宽大于200 ns,前沿时间小于90 ns。整个装置在不加散热系统的情况下,可连续工作1 min以上。     

基于TTL数字电路控制的高压脉冲源

给出了一种基于TTL数字电路作为高压脉冲源触发控制单元的设计原理和方法。介绍了高压脉冲源的工作原理,设计了一台脉冲输出幅度5 kV、脉冲宽度大于200 s及脉冲前沿小于30 ns的高压脉冲源。将触发控制单元和前级开关金属氧化物半导体场效应管（MOSFET）组合成一体,控制后级气体高压开关管放电输出高压脉冲信号。实验结果验证了所采用的设计原理及方法的可行性,给出了单次触发情况下的实验结果。     

高压双扩散漏端MOS晶体管双峰衬底电流的形成机理及其影响

利用0.15μm标准CMOS工艺制造出了工作电压为30V的双扩散漏端MOS晶体管(double diffused drain MOS, DDDMOS).观察到DDDMOS的衬底电流-栅压曲线(I_b-V_g曲线)有两个峰.通过实验和TCAD模拟揭示了DDDMOS衬底电流的形成机理,发现衬底电流第一个峰的成因与传统MOS器件相同;第二个峰来自于发生在漂移区远离沟道一侧高场区的碰撞离化电流.通过求解泊松方程和电流连续性方程,分析了器件的物理和几何参数对导致衬底电流重新上升的漂移区电场的影响.在分析了DDDMOS衬底电流的第二个峰形成机理的基础上,考察了其对器件的可靠性的影响. 关键词： 高压器件 衬底电流 可靠性     

高压电晕特性的研究

介绍应用图像增强技术解决高压电晕观测中存在问题的实验原理和依据,分析高压电晕图像的特性,讨论利用图像增强技术研制的高压电晕观测仪器的特点,举例说明该系统在输电导线电晕放电特性研究中的应用,最后指出图像增强技术在高压电晕观测中的应用前景。